Constant-current generator.



PATENTED NOV. 6, 1906.

APPLICATION FILED APR. 3, 1905.

HIFFERE/VT/ALL y M MILGH CONSTANT GURRENTGENERATOR.

com/ 0 M] WOU/VD WOUND UNITED STATES PATENT OFFICE.

MAURICE MILCH, OF SOHENECTADXI NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CONSTANT-CURRENT GENERATOR.

Patented Nov. 6, 1906.

To all whom it may concern:

Be it known that I, MAURICE MILcH, a subject of the Emperor of AustriaHungary, residing at Schenectady, county of Schenectady, State of New York, haveinvented certain new and useful Improvements in Constant-Current Generators, of which'the folthe poles produced by the coils O lowing is a specification.

My invention relates to dynamo-electric machines; and its object is to provide a generator adapted to give a practically co tantcurrent output, although operated at arying speeds or with a varying resistance connected across its terminals.

My invention consists in so arranging the machine that the current delivered by the machine'produces a strong cross-field, leading off by a set of auxiliary brushes acurrent induced in the armature by the cross-field and utilizing this current for demagnetizing the main field of the machine.

' My invention will best be understood by reference to the accompanying drawing, which shows somewhat diagrammatically a constant-current generator arranged in accordance with my invention.

In the drawing, A represents the armature,

provided with a set of brushes B B, fromically equivalent to a single ole and the poles 3 and 4 to a single pole o the opposite polarity.

The brushes B B, which supply the external circuit, are placed in the usual manner at or near the neutral points with res ect to Cl 7 The coils C O are shown connected in shunt to the machine terminals T T. The current flowing through the brushes B B tends to produce a magnetization of the machine at right angles to the magnetization produced by the shunt-coils O Cthat is, it tends to make the poles 1 and 4 of one polarity and 2 and 3 of the other polarity. This tendency is opposed -machine is thus kept substantial 'over a wide variation of speed or with wide and overwhelmed by a set of coils D D, which are connected in series with the brushes B B and with the external circuit. These coils, overpowering the magnetizing action of the armature-current between brushes B B, produce a magnetization proportional to the current in the external circuit at right angles to that produced by the shunt-coils G O. This cross-magnetization induces an electromotive force in the armature which is a maximum at the points displaced ninety degrees from the brushes B B. At these oints a second set of brushes B B is place and in series with these brushes are connected two sets of coils E E and F F. The coils E E as sist the coils D in producing the cross-magnetization of the machine, while the coils F F oppose the magnetizing eflect of the main coils O C. i

The operation is then as follows: A slight increase in the current in the external circuit, due either to an increase of speed of the machine or a decrease of resistance in the external circuit, increases the cross-magnetizing eflect of the coils D D, and consequently increases the potential between the brushes B B. This increased otential increases the current in the coils E, which further increases the potential across the brushes B B, and the increase of current in the coils F F reduces the main-field magnetization of the machine. The current output of the variations of resistance in the external circuit.

Although I have shown the arrangement of field-coils which I believe to be best adapted to securing the desired results, nevert less a number of variations may be made without departing from my invention. Thus, for instance, since the armature-current between the brushes B B tends to cross magnetization of the mac c this current itself may be utilized for roducing the cross-magnetization, the coils D being y constant roduce a IOO omitted or connected, so as to assist the ef- 7 feet of the armature-current. This arran e ment, however, would be less favorable or commutation than the arrangement which I magnetization in the opposite direction. Snnilarly, since the current flowing in the armature between the brushes B. B tends to demagnetize the main field the current in the armature alone-might be utilized for the demagnetizin eflect by simply connecting the brushes B %3 together, omitting the coils E and F. A large cross-current would then be required, since the armature-turns are comparativel few in number, and this large current woul d heat the armature unnecessarily and would also tend to produce s arking at the brushes B B. Consequently prefer to employ the auxiliary-field coils inserted in the connection between the brushes B B. These field-coils may be of as great a number of turns as desired, so that the current flowing through the brushes B B may be very small. It is not essential that the coils E E should be employed; but they are advantageous in making the machine more responsive to variations in the armature-current. An increase of potential between the brushes B B increases the current-flow through the coils E E, and the increase of current-flow through the coils E E increases the potential across the brushes B B. The effect is consequently cumulative, and a very slight change of current in the external circuit is suflicient to produce a very marked variation in the magnetization of the machine.

I do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the a pended claims to cover all modifications w ch are within the scope of my invention.

What I claim asnew, and desire to secure by Letters Patent of the United States, is

1. In a dynamo-electric machine, mainfield coils, an armature, commutator-brushes arranged to lead ofi the current induced in the armature by said main-field coils and connected to an external circuit, means for producing a cross-magnetization increasing with increase in the armature-current, auxiliary commutator-brushes arranged to lead ofl the current induced in the armature by said cross-magnetization, and connections whereby the current led off by said auxiliary brushes opposes the main-field ma netization.

2. In a dynamo-electric machine, main.- field coils, an armature, commutatonbrushes arranged to lead off the current induced in said armature by said main-field coils and connected to an external circuit, auxiliary-field coils in series with said brushes arranged to overpower the armature magnetization and to produce a cross magnetization increasing with an increase in the armature-current, auxiliary commutator-brushes arranged to lead off the current induced in the armature by said cross-magnetization, and connec tions whereby the current led off by said auxiliary brushes opposes the main field magnetization.

3. In a dynamo-electric machine, mainfield coils, an armature, commutator-brushes arranged to lead off. the current induced 1n the armature by said main-field 0011s and connected to an external circuit, means for producing a cross-magnetization increasing with increase in the armature-current, auxiliary commutator-brushes arranged to lead off the current induced in the armature by said cross-magnetization, and auxiliary-field coils in series with said'auxiliary brushes arranged to oppose the main-field coils.

' 4. n a dynamo-electric machlne, ma1n field coils, an armature, commutator-brushes arranged to lead off the current induced in the armature by said main-field 0011s and connected to an external circuit, means for producing a cross-magnetization increasing With increase in the armature-current, auxiliary commutator-brushes arranged to lead off the current induced in the armature by said cross magnetization, connections whereby the current led off by said auxiliary brushes opposes the main-field magnetization, and auxiliary field coils in series with said brushes arranged to increase said cross-magnetization.

5. In a dynamo-electric machine, mainfield coils, an armature, commutator-brushes arranged to lead olf the current induced in the armature by said main-field coils and connected to an external circuit, means for producing a cross-magnetization increasiug with increase in the armature-current, auxiliary commutator-brushes arranged to lead off the current induced in the armature by said cross-magnetization, and two sets of auxiliary-field coils supplied from said auxiliary brushes, one set being arranged to oppose the main-field coils and the other to increase the cross-magnetization.

, 6. In a dynamo-electric machine, mainfield coils, an armature, commutator-brushes arranged to lead oif the current induced in said armature by said main-field coils and connected to an external circuit, auxiliaryfield coils in series with said brushes arranged to overpower the armature magnetization and to produce a cross-magnetization increasing with an increase in the armaturecurrent, auxiliary commutator-brushes arranged to lead off the current induced in the armature by said cross-magnetization, and a econd set of auxiliary-field coils supplied trom said auxiliary brushes and arranged to opposethe main-field coils.

7. In a dynamo-electric machine, mainfield coils, an armature, commutator-brushes arranged to lead off the current induced in said armature by said main-field coils and connected to an external circuit, auxiliaryfield coils in series with said brushes arranged to overpower the armature magnetization and to produce a cross-magnetization increasing with increase in the armature-current, auxiliary commutator-brushes arranged to lead off the currentinduced in the armature by said cross-magnetization, and two sets of auxiliary-field coils supplied from said auxiliary brushes, one of said sets being arranged to oppose themain-field coils and theother to increase the cross-magnetization.

8. In a dynamo-electric machine, mainfield coils, an armature, commutator-brushes arranged on a line displaced substantially l ninettyelectrical degrees from the line of the main-field ma etization, auxiliary brushes on the line of eld-magnetization, and auxiliary-field coils supplied from said auxiliary brushes and arranged to produce a cross- ,[5 magnetization of the machine.

In witness whereof I have hereunto set my hand this 1st day of April, 1905.

MAURICE MILOH. Witnesses:

BENJAMIN B. HULL, HELEN ORFORD. 

